"Predestination" and the Judgment Hour
The natural man is dead in trespass and sin. He is totally incapable of coming to God except as God draws Him by the power of the Holy Spirit. It is only by virtue of the ministry of our Lord Jesus Christ as the mediator and intercessor between God and Man, that the Spirit, through the preaching and teaching of the Gospel, can come to Man with the offer of forgiveness of sin and eternal life through faith in Christ's sinless life and atoning death upon the cross of Calvary. As the call of the Gospel goes into all the world the attending Holy Spirit brings conviction of sin and righteousness and judgment to the lost sons and daughters of Adam and invites all to believe in Christ and repent of their sins.
Man cannot of himself repent or come to Christ without the pleading and drawing of the Spirit of Christ. "Many" are called but "few" are "chosen" however, and those who reject and rebuff the pleadings of the Spirit upon their hearts eventually are unable to hear and respond to the call through their continual hardening of their hearts through unbelief.
To those who harden their hearts, the Spirit is eventually withdrawn and their hearts are "hardened" in unbelief as God withdraws His tender pleading Spirit. Thus those who themselves "harden" their hearts in unbelief commit the unpardonable sin of rejection of the Holy Spirit, and God then "hardens" their hearts by withdrawing the Spirit. The lost are then left without the pleading of the Spirit upon their hearts and are left without hope and without God in the world awaiting the Day of the Lord and are reserved unto judgment and destruction. There comes a time in the lives of all who reject the call of the Lord when they are hardened beyond the reach of salvation.
This is what Paul is referring to in Romans 9 regarding Pharaoh and God's longsuffering patience with him. Finally after resisting God's Spirit, Pharaoh was "hardened" in unbelief and became among those who are "predestined" unto eternal destruction for God has hardened his heart.
It is not the will of God that any should be lost. He pleads with all to repent and believe, but His Spirit will not always strive with men who harden their hearts and finally they are given up to the Evil One to share his fate. God does not foreordain any to be destroyed but He will "harden" the wicked in their own "hardness" of their hearts. It is a fearful thing to resist the call of God's grace in the Gospel for it is a fearful thing to fall into the hands of the Living God.
As we are admonished in Hebrews 3:12
"Take heed, brethren, lest haply there shall be in any one of you an evil heart of unbelief, in falling away from the living God, but exhort one another day by day, so long as it is called Today, lest any one of you be hardened by the deceitfulness of sin. For we are become partakers of Christ, if we hold fast the beginning of our confidence firm unto the end. While it is said, Today if ye shall hear His voice, Harden not your hearts, as in the provocation."